Changes in kinematic variables observed during pressure-induced forelimb lameness in adult horses trotting on a treadmill

OBJECTIVE: To determine whether kinematic changes induced by heel pressure in horses differ from those induced by toe pressure. ANIMALS: 10 adult Quarter Horses. PROCEDURE: A shoe that applied pressure on the cuneus ungulae (frog) or on the toe was used. Kinematic analyses were performed before and after 2 levels of frog pressure and after 1 level of toe pressure. Values for stride displacement and time and joint angles were determined from horses trotting on a treadmill. RESULTS: The first level of frog pressure caused decreases in metacarpophalangeal (fetlock) joint extension during stance and increases in head vertical movement and asymmetry. The second level of frog pressure caused these changes but also caused decreases in stride duration and carpal joint extension during stance as well as increases in relative stance duration. Toe pressure caused changes in these same variables but also caused maximum extension of the fetlock joint to occur before midstance, maximum hoof height to be closer to midswing, and forelimb protraction to increase. CONCLUSION AND CLINICAL RELEVANCE: Decreased fetlock joint extension during stance and increased head vertical movement and asymmetry are sensitive indicators of forelimb lameness. Decreased stride duration, increased relative stance duration, and decreased carpal joint extension during stance are general but insensitive indicators of forelimb lameness. Increased forelimb protraction, hoof flight pattern with maximum hoof height near midswing, and maximum fetlock joint extension in cranial stance may be specific indicators of lameness in the toe region. Observation of forelimb movement may enable clinicians to differentiate lameness of the heel from lameness of the toe.     

The forelimb in walking horses: 1. Kinematics and ground reaction forces

Video (60 Hz) and force (2000 Hz) data were collected from 5 sound horses during walking. Forelimb data were analysed for 8 strides (4 left, 4 right) per horse to determine sagittal plane kinematics and ground reaction forces (GRFs). The results suggested that brachial rotation was responsible for protraction and retraction of the limb as a whole, while rotations of the scapula and antebrachium elevated the distal limb during breakover and early swing then lowered it in preparation for ground contact. The coffin joint was flexed maximally at the time of peak longitudinal braking force, which occurred during breakover of the contralateral forelimb. The metacarpus was vertical at 28% stride. This was considerably earlier than the change from a braking to a propulsive longitudinal force (34% stride), which coincided with maximal extension of the fetlock joint. The longitudinal propulsive force peaked just after contact of the contralateral forelimb. During the swing phase the joints distal to the shoulder showed a single flexion cycle that peaked at 76% stride at the carpus, 81% stride at the fetlock and 84% stride at the elbow and coffin joints. The coffin and shoulder joints began to extend in the terminal swing phase and continued to extend through ground contact and early stance. The results provide normative data that will be applied in detecting changes in kinematics and ground reaction forces that are associated with specific lamenesses.     

Lameness diagnosis and treatment in the quarter horse racehorse

Lameness problems constitute a major part of racing Quarter Horse practice. This article considers the diagnosis, prognosis, and treatment of the frequently encountered lamenesses. The main conditions included are synovitis, intra-articular fractures, osteochondritis dissecans, and degenerative joint disease as they relate to the coffin, fetlock, carpal, and tarsal joints. Intra-articular injection techniques and medications are discussed because of the frequency of joint disease. Bucked shins and stress fractures are also reviewed.     

The hindlimb in walking horses: 1. Kinematics and ground reaction forces

The objective was to study associations between kinematics and ground reaction forces in the hindlimb of walking horses. Video (60 Hz) and force (2000 Hz) data were gathered for 8 strides from each of 5 sound horses during the walk. Sagittal plane kinematics were measured concurrently with the vertical and longitudinal ground reaction forces. The hindlimb showed rapid loading and braking in the initial 10% stride. The stifle, tarsal and coffin joints flexed and the fetlock joint extended during this period of rapid loading. The vertical ground reaction force showed 2 peaks separated by a dip; this pattern was similar to the fetlock joint angle-time graph. Peaks in the longitudinal ground reaction force did not appear to correspond with kinematic events. Total braking impulse was equal to total propulsive impulse over the entire stride. Flexion and extension of the hip were responsible for protraction and retraction of the entire limb. Maximal protraction occurred shortly before the end of swing and maximal retraction occurred during breakover. During the middle part of stance the tarsal joint extended slowly, while the stifle began to flex when the limb was retracted beyond the midstance position at 28% stride. Flexion cycles of the stifle and tarsal joints were well coordinated during the swing phase to raise the distal limb as it was protracted. The results demonstrate a relationship between limb kinematics and vertical limb loading in the hindlimbs of sound horses. Future studies will elucidate the alterations in response to lameness.     

Observations on the in vitro behavior of digital tendons

The force/strain behavior of the common and lateral extensor tendons, the extensor branches of the interosseus muscle, and the superficial flexor tendon have been examined in vitro. The flexor tendon acted as a hard-spring with an initial large strain with small load followed by progressively less strain with increasing load, The distal part of the common extensor tendon and the extensor branches behaved in the same manner during dorsiflexion of the fetlock joint/palmar flexion of the coffin joint. The common extensor tendon behaved in a softening manner during palmar flexion of the fetlock and coffin joints while the lateral extensor and the extensor branches behaved in a nearly linear manner.     

Neoplasms in cattle: A survey of 372 neoplasms examined at the Ruakura Veterinary Diagnostic Station

Intra-articular sodium hyaluronate was used to treat 16 horses with osteo-arthrosis of the carpus, fetlock, hock and coffin joints. In 11of these horses lameness was completely relieved. In addition, 5 horses that underwent carpal surgery for the removal of chip fractures received sodium hyaluronate 10–14 days later. In thesecases, it appeared to have a beneficial effect, resulting in a greater range of movement of the carpus soon after surgery and less swelling of the joint capsule. The results of synovial fluid analysis in horses with osteo-arthrosis, and with carpal fractures, are also presented.     

A Quantitative Review of the Equinalysis System for Equine Locomotion Analysis

Movement analysis techniques allow objective and quantitative assessment of kinematic gait analysis. Consistent repeatability of the kinematic data is essential for such assessments. This study investigated whether the repeatability of a standardized Equinalysis Elite gait analysis system is sufficient to allow its use in clinical evaluation of equine lameness with reliable documentation of individual locomotion patterns. The extent to which examinations on different days affected the results when a standardized protocol was used was investigated. The repeatability of distal limb kinematics in nine sound horses over three successive days at one location was investigated. Measurements were performed at the examination area, for three motion cycles at the walk and trot, in each direction per day. Skin markers were placed on the lateral aspect of the coffin joint, forelimb fetlock joint, hindlimb fetlock joint, carpus, tarsus, elbow, and stifle, at clipped sites marked with a permanent marker. The inter-day repeatability of angular measurements of the carpus, tarsus, forelimb fetlock, and hindlimb fetlock joints was determined. A low degree of inter-day repeatability was found with statistically significant (P ≤ .05) differences between findings on different days, observed in the time-angle diagrams of left and right carpus, tarsus, forelimb fetlock, and hindlimb fetlock joints of all horses, at both walk and trot. The standardized Equinalysis Elite system for gait analysis of distal limb kinematics in the horse did not provide highly repeatable data in this setting.     

The hindlimb in walking horses: 2. Net joint moments and joint powers

The objective of the study was to describe net joint moments and joint powers in the equine hindlimb during walking. The subjects were 5 sound horses. Kinematic and force data were collected synchronously and combined with morphometric information to determine net joint moments at each hindlimb joint throughout stance and swing. The results showed that the net joint moment was on the caudal/plantar side of all hindlimb joints at the start of stance when the limb was being actively retracted. It moved to the cranial/dorsal side around 24% stride at the hip and stifle and in terminal stance at the more distal joints. It remained on the cranial/dorsal side of all joints during the first half of swing to provide active limb protraction, then moved to the caudal/plantar aspect to reverse the direction of limb motion prior to ground contact. The hip joint was the main source of energy generation throughout the stride. It was assisted by the tarsal joint in both stance and swing phases and by the fetlock joint during the stance phase. The coffin joint acted as an energy damper during stance, whereas the stifle joint absorbed almost equal amounts of energy in the stance and swing phases. The coffin and fetlock joints absorbed energy as the limb was protracted and retracted during the swing phase, suggesting that their movements were driven by inertial forces. Future studies will apply these findings to detect changes in the energy profiles due to specific soft tissue injuries.     

Three-dimensional kinematics of the distal forelimb in horses trotting on a treadmill and effects of elevation of heel and toe

REASONS FOR PERFORMING STUDY: Comprehensive understanding of the 3-dimensional (3D) kinematics of the distal forelimb and precise knowledge of alterations induced by dorsopalmar foot imbalance remains incomplete because in vivo studies performed with skin markers do not measure the actual movements of the 3 digital joints. OBJECTIVE: To quantify the effects of 6 degree heel or toe wedges on the 3D movements of the 4 distal segments of the forelimb in horses trotting on a treadmill. METHODS: Three healthy horses were equipped with ultrasonic markers fixed surgically to the 4 distal segments of the left forelimb. The 3D movements of these segments were recorded while horses were trotting on a treadmill. Rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained with 6 degree heel or toe wedges were compared to those obtained with flat standard shoes. RESULTS: Use of heel wedges significantly increased maximal flexion and decreased maximal extension of the proximal (PIPJ) and distal (DIPJ) interphalangeal joints. Inverse effects (except for PIPJ maximal extension) were observed with the toe wedges. In both cases, neither flexion-extension of the metacarpophalangeal joint nor extrasagittal motions of the digital joints were statistically different between conditions. CONCLUSIONS: At a slow trot on a treadmill, heel and toe wedges affect the sagittal plane kinematics of the interphalangeal joints. POTENTIAL RELEVANCE: Better understanding of the actual effects of toe and heel wedges on the 3D kinematics of the 3 digital joints may help to improve clinical use of sagittal alteration of hoof balance in the treatment of distal forelimb injuries.     

Changes on radiographs at Thoroughbred yearling sales: Prevalence and significance

Examination of Thoroughbred yearlings at public auction is a special form of prepurchase examination since the clinician cannot be as thorough as in clinical situations. Yearlings are purchased based on visual and limited physical examinations and evaluation of presale radiographs and upper respiratory tract endoscopic examination. The prevalence and clinical relevance of radiographic changes has been the subject of our recent publications and a summary of our results is presented here. Radiographic changes were most common in the fetlock joints and 1127 forelimb and 1102 hindlimb fetlock radiographic series were examined. Flattened areas of the distal palmar aspect of the distal articular surface of the third metacarpal bone (McIII) were found in 41% of yearlings and had neither an effect on performance nor caused the subsequent development of clinical problems. Flattening (10%) or radiolucency (17%) of the dorsal aspect of the distal sagittal ridge of McIII was common and had no effect of these 2 parameters. Thirty of 1130 yearlings that had complete carpal radiographic examinations had signs of dorsal medial middle carpal disease. The presence of dorsal medial middle carpal joint lesions affected the horse’s ability to start a race and increased the incidence of clinical problems. The most common finding on carpal radiographs was circular radiolucencies in the ulnar carpal bone but the presence of this finding neither affected the ability to start nor was associated with clinical problems. Forty-eight of 1101 yearlings with complete tarsal radiographic examinations had concavity or fragmentation of the cranial intermediate ridge of the distal tibia, but there was no effect on racing performance. The changes most commonly observed in the distal tarsal joints were the presence of osteophytes or enthesophytes involving the distal intertarsal or tarsometatarsal joints. The presence of osteophytes or enthesophytes involving the distal intertarsal or tarsometatarsal joints were the only changes significantly associated with starting a race, but the effect was small. There were 600 yearlings with stifle radiographs, but in only 170 of them could the medial femoral condyle and proximal tibia be evaluated. Thirty-four yearlings had defects with or without fragments on the lateral trochlear ridge of the femur and there were no significant associations with any outcome except that they were more likely to have surgical treatment.     

Three-dimensional kinematics of the equine interphalangeal joints: articular impact of asymmetric bearing

The objective of this study was to assess the effects of asymmetric placement of the foot on the three-dimensional motions of the interphalangeal joints. Four isolated forelimbs were used. Trihedrons, made of three axes fitted with reflective markers, were screwed into each phalanx. They allowed to establish a local frame associated with each bone and thus to define the spatial orientation of the phalanges. The limbs were then placed under a power press, and subjected to compression with gradually increasing force (from 500 to 6 000 N). The procedure was performed in neutral position and with the lateral or medial part of the foot raised by a 12 degrees wedge. Flexion, collateromotion (passive abduction/adduction) and axial rotation of the interphalangeal joints were measured using a cardan angle decomposition according to the principle of the "Joint Coordinate System" described by Grood and Suntay. Raising the lateral or medial part of the hoof induced collateromotion (about 5.6 degrees +/- 0.8) and axial rotation (about 6.5 degrees +/- 0.5) of the distal interphalangeal joint. The proximal interphalangeal joint underwent axial rotation (about 4.7 degrees +/- 0.5 at 6 000 N) and slight collateromotion. Both interphalangeal joints underwent collateromotion in the direction of the raised part of the foot (i.e., narrowing of the articular space on the side of the wedge), whereas axial rotation occurred in the direction opposite to the raised part of the foot. These results confirm the functional importance of interphalangeal joint movements outside the sagittal plane. In particular they demonstrate the involvement of the proximal interphalangeal joint in the digital balance. These data are helpful for the identification of biomechanical factors that may predispose to interphalangeal joint injury. Also the data may be of use for the rational decision making with respect to exercise management and corrective shoeing of the lame horse.     

Net joint moments and joint powers in horses with superficial digital flexor tendinitis

OBJECTIVE: To determine whether analysis of net joint moments and joint powers is a suitable technique for evaluation of mechanics and energetics of lameness in horses and to measure effects of superficial digital flexor tendinitis. ANIMALS: 6 sound horses. PROCEDURE: Horses were evaluated before (sound evaluation) and after (lame evaluation) induction of superficial digital flexor tendinitis in 1 forelimb by injection of collagenase. Recordings were made with an optoelectronic system and a force plate as horses trotted. Net joint moments and joint powers in the sagittal plane at each joint in the forelimbs during the stance phase were determined. Peak values were determined, and mechanical energy absorbed and generated at each joint was calculated. Comparisons were made between contralateral limbs during sound and lame evaluations. RESULTS: Lame limbs had significant reductions in peak values for net joint moments on the palmar aspect of metacarpophalangeal (fetlock), carpal, and humeroulnar joints. Total energy absorbed was significantly lower at every joint in lame limbs, compared with compensating limbs. CONCLUSIONS AND CLINICAL RELEVANCE: Horses with superficial digital flexor tendinitis had significant differences between lame and compensating limbs for net joint moments and joint powers at all joints, indicating that the gait of horses with superficial digital flexor tendinitis is energetically inefficient. Assessment of net joint moments and joint powers is a useful tool in evaluating equine lameness.     

H-PSGAG concentration in the synovial fluid of the equine antebrachiocarpal, metacarpophalangeal, coronopedal and tibiotarsal joints following a 500 MG i

Eight mature horses were administered a single intramuscular injection of 500 mg polysulfated glycosaminoglycan (PSGAG) labeled with 2.044 mCi tritium. Synovial fluid samples were collected from the antebrachiocarpal (carpal), metacarpophalangeal (fetlock), tibiotarsal (hock) and coronopedal (coffin) joints prior to injection and at 2, 4, 8, 12, and 24 hours after injection. The samples were subjected to scintillation counting in decays per minute and were converted to μg PSGAG per ml. The levels achieved in the synovial fluid of the various joints were compared to levels of PSGAG described as adequate to inhibit enzymes which degrade articular cartilage matrix components and hyaluronic acid and adequate to stimulate production of new matrix components and hyaluronic acid in diseased joints.Mean synovial fluid ³H-PSGAG levels indicated that peak concentrations of ³H-PSGAG were achieved 2 hours post injection in all joints and that these concentrations were within the therapeutic range for PSGAG. The peak concentrations were not significantly different among the joints except between the antebrachiocarpal and the metacarpophalangeal joints. The areas under the concentration-time curves (AUC) for each joint were computed by the trapezoidal method from hour 0 through hour 24 and by empirical exponential decay beyond hour 24. These values were subjected to an analysis of variance (ANOVA). The overall multivariate test of AUC among all joints was not significant.The data from this study indicate that a single intramuscular 500 mg injection of PSGAG provided therapeutic levels of the drug in the equine antebrachiocarpal, metacarpophalangeal, tibiotarsal, and coronopedal joints within 2 hours of injection. While there were differences in levels between joints at certain time points, the AUC values suggest similar distribution of the drug in all joints tested.     

Wedge and Eggbar Shoes Change the Pressure Distribution Under the Hoof of the Forelimb in the Square Standing Horse

The shoe types most commonly applied to horses with navicular disease or other forms of palmar heel pain are shoes with heel wedges and eggbar shoes, although their efficacy has been a matter of debate among veterinarians and farriers for centuries. To quantify the effect of these different types of “navicular” shoeing on static hoof pressure distribution, 6 warmblood horses were shod with 6° wedge, eggbar, and plain shoes. While standing square with weight evenly distributed across both forelimbs, the center of pressure and pressures at selected areas of interest (AOI: toe, medial and lateral toe, medial and lateral heel) were measured using a Footscan (RsScan International, Belgium) pressure plate in a Latin square design using the plain shoe as a reference.Wedge shoes did not provide a significant shift in the center of pressure. The application of eggbar shoes did not alter the relative position of the center of pressure under the hoof. However, the absolute distance from the toe to the center of pressure was significantly larger with eggbar shoes (77 + 12 mm) compared with plain and wedged shoes (70 ± 8 mm, P < .05) resulting in an absolute, caudal shift of the center of pressure. When pressure (N/cm²) values at the five AOIs were averaged for each shoe type, the wedge and eggbar shoe recordings showed a significantly lower mean pressure than plain shoes (P < .05).In conclusion, mean AOI pressures decreased with wedge and eggbar shoes, and eggbar shoes provided a caudal shift in the center of pressure. These effects are believed to decrease the moment of the coffin joint and reduce the pressure on the navicular bone. Thus, the findings of this study might contribute to the scientific evidence of efficacy of the use of wedge and eggbar shoes in “navicular” lame horses.     

Kinematics of the hind limb in trotting horses after induced lameness of the distal intertarsal and tarsometatarsal joints and intra-articular administration of anesthetic

OBJECTIVE: To identify hind limb and pelvic kinematic variables that change in trotting horses after induced lameness of the distal intertarsal and tarsometatarsal joints and after subsequent intra-articular administration of anesthetic. ANIMALS: 8 clinically normal adult horses. PROCEDURE: Kinematic measurements were made before and after transient endotoxin-induced lameness of the distal intertarsal and tarsometatarsal joints and after intra-articular administration of anesthetic. Fourteen displacement and joint angle (metatarsophalangeal [fetlock] and tarsal joints) measurements were made on the right hind limb, sacrum, and the right and left tubera coxae. Kinematic measurements were compared by general linear models, using a repeated measures ANOVA. Post hoc multiple comparisons between treatments were evaluated with a Fisher least squared difference test at alpha = 0.05. RESULTS: After lameness induction, fetlock and tarsal joint extension during stance decreased, fetlock joint flexion and hoof height during swing increased, limb protraction decreased, and vertical excursion of the tubera coxae became more asymmetric. After intra-articular administration of anesthetic, limb protraction returned to the degree seen before lameness, and vertical excursion of the tubera coxae became more symmetric. CONCLUSIONS AND CLINICAL RELEVANCE: Increased length of hind limb protraction and symmetry of tubera coxae vertical excursion are sensitive indicators of improvement in tarsal joint lameness. When evaluating changes in tarsal joint lameness, evaluating the horse from the side (to assess limb protraction) is as important as evaluating from the rear (to assess pelvic symmetry).     

Compensation for changes in hoof conformation between shoeing sessions through the adaptation of angular kinematics of the distal segments of the limbs of horses

OBJECTIVE: To determine the mechanism that enables horses to partially counteract the shift of the center of pressure under the hoof induced by changes in hoof morphology attributable to growth and wear during a shoeing interval. ANIMALS: 18 clinically sound Warmblood horses. PROCEDURES: Horses were evaluated 2 days and 8 weeks after shoeing during trotting on a track containing pressure-force measuring plates and by use of a synchronous infrared gait analysis system set at a frequency of 240 Hz. All feet were trimmed toward straight alignment of the proximal, middle, and distal phalanges and shod with standard flat shoes. Results-Temporal characteristics such as stance time and the time between heel lift and toe off (ie, breakover duration) did not change significantly as a result of shoeing interval. Protraction and retraction angles of the limbs did not change. Compensation was achieved through an increase in the dorsal angle of the metacarpohalangeal or metarsophalangeal (fetlock) joint and a concomitant decrease of the dorsal angle of the hoof wall and fetlock. There was an additional compensatory mechanism in the hind limbs during the landing phase. CONCLUSIONS AND CLINICAL RELEVANCE: Horses compensate for changes in hoof morphology that develop during an 8-week shoeing interval such that they are able to maintain their neuromuscular pattern of movement. The compensation consists of slight alterations in the angles between the distal segments of the limb. Insight into natural compensation mechanisms for hoof imbalance will aid in the understanding and treatment of pathologic conditions in horses.     

The forelimb in walking horses: 2. Net joint moments and joint powers

The objective was to measure the net joint moments and joint powers for the joints of the equine forelimb during the walk. Videographic and force data were combined with morphometric information using an inverse dynamics method. During stance phase the predominant joint moment was on the palmar aspect of all forelimb joints except the shoulder, where the peak moment was considerably higher than at any other joint. The entire forelimb showed net energy absorption in both stance and swing phases. The elbow was the only joint that showed net generation of energy, which was used to maintain the limb in extension in early stance as the horse's body vaults over the limb and to drive protraction and retraction of the limb during swing. The carpus aligned the limb into a supportive strut, but did not play an important role in energy absorption or generation. A small burst of positive work on the flexor aspect at the start of breakover indicated that the carpus played an active role in initiating breakover during walking. The fetlock functioned elastically to store and release strain energy during stance. The coffin joint acted as an energy damper during most of stance with a small burst of energy generation on the flexor aspect as the joint flexed during breakover. The magnitude of the peak joint power during swing decreased in a proximal to distal sequence. It is concluded that the elbow joint is the main site of energy generation. The shoulder and coffin joints act as energy dampers during stance. The distal joints had very low joint powers and appeared to be driven by inertial forces during the swing phase. This information will be applied to describe how horses compensate for different lamenesses in terms of redistributing the functions of energy generation and absorption between joints.     

Postnatal contracture of young horses

Three forms of postnatal contractures of the forelimb of young horses are: primary suspensory ligament contracture, primary deep flexor contracture, and combined contracture (pain contracture).Mechanical models are developed which demonstrate theoretically that (1) suspensory contracture is the result of a too small hoof angle followed and/or accompanied by a too rapid increase of the weight borne by the leg (whether as the result of lameness or too large a rate of gain of body weight). (2) Deep flexor contracture is the result of inadequate wearing of the bearing surface of the hoof wall, however induced, (3) Pain contracture is the result of decreased weight bearing.In all cases the contracture progresses as the shortened tendons cross-link and thereby become stronger in the shortened position. Once the cycleof suspensory contracture has been induced, secondary shortening of the superficial flexor, and eventually the deep flexor, can occur. There is less tendency for secondary contracture with primary deep flexor contracture, though the superficial flexor may shorten in an advanced case.The absence of clinically obvious postnatal contractures of the rearlegs is related to the fact that the deep flexor check ligament is small or absent in the rearleg and therefore to the fact that the deep flexor operates over the tibiotarsal as well as the coffin and fetlock joints.     

Quantification of skin displacement near the carpal, tarsal and fetlock joints of the walking horse

A technique enabling simultaneous visualisation of skin and underlying bony structures in the walking horse was used to quantify skin displacements on the lateral surface of carpal, tarsal and fetlock joints. The technique employed implanted light-emitting-diodes (LEDs) for marking the bone, and self adhesive spot labels for marking the overlying skin. Photographic recordings were made. Skin displacement was measured in six Dutch Warmblood horses. Mean total displacements and mean displacement per degree of change of joint angle were calculated. Displacements at the level of the fetlock joints appeared to be generally small (less than or equal to 2 mm), but displacements up to 2 cm were measured in the distal tibia. Displacements of this magnitude are of importance for the interpretation of results obtained by modern gait analysis techniques.     

Detection of lameness and determination of the affected forelimb in horses by use of continuous wavelet transformation and neural network classification of kinematic data

OBJECTIVE: To investigate continuous wavelet transformation and neural network classification of gait data for detecting forelimb lameness in horses. ANIMALS: 12 adult horses with mild forelimb lameness. PROCEDURE: Position of the head and right forelimb foot, metacarpophalangeal (ie, fetlock), carpal, and elbow joints was determined by use of kinematic analysis before and after palmar digital nerve blocks. We obtained 8 recordings from horses without lameness, 8 with right forelimb lameness, and 8 with left forelimb lameness. Vertical and horizontal position of the head and vertical position of the foot, fetlock, carpal, and elbow joints were processed by continuous wavelet transformation. Feature vectors were created from the transformed signals and a neural network trained with data from 6 horses, which was then tested on the remaining 2 horses for each category until each horse was used twice for training and testing. Correct classification percentage (CCP) was calculated for each combination of gait signals tested. RESULTS: Wavelet-transformed vertical position of the head and right forelimb foot had greater CCP (85%) than untransformed data (21%). Adding data from the fetlock, carpal, or elbow joints did not improve CCP over that for the head and foot alone. CONCLUSIONS AND CLINICAL RELEVANCE: Wavelet transformation of gait data extracts information that is important for the detection and differentiation of forelimb lameness of horses. All of the necessary information to detect lameness and differentiate the side of lameness can be obtained by observation of vertical head movement in concert with movement of the foot of 1 forelimb.